P474: PIEZO1 AND THE THERAPEUTIC POTENTIAL OF MECHANORECEPTORS IN ACUTE MYELOID LEUKAEMIA
Authors: M. Velasco Estevez, A. Fernandez, A. Otero-Sobrino, P. Aguilar-Garrido, M. A. Navarro-Aguadero, R. Sanchez, A. Gimenez Sanchez, V. Garrido Garcia, L. Carneros Blanco, J. Martinez-Lopez, M. Gallardo
Journal: HemaSphere (2022)

Background:Mechanotransduction is the process through which cells sense the mechanical input in and out the cell, and translate it into biochemical signals adapt and respond. In the past few years, it has been observed the important contribution of mechanical input in cell differentiation, fate, stemness, senescence and cancer, amongst others. Piezo1 is a mechanoreceptor discovered in 2010 and constitutes a cation channel activated through stretch and shear flux leading to a calcium influx in the cell that activates a myriad of different pathways. Interestingly, despite being a mechanoreceptor, Piezo1 can also be activated through a small molecule, Yoda-1, and blocked by a peptide, GsMTx4, allowing the pharmacological study of this receptor. Mutations in PIEZO1 lead to pathologies as Xerocitosis hereditaria and it has been linked to erythroid formation. However, the expression and role of Piezo1 in haematological malignancies is yet to be explored Aims: We aim to analyse the expression of Piezo1 in Acute Myeloid Leukaemia (AML) and healthy donors, and investigate the putative role of Piezo1 in cell differentiation and fate as well as its therapeutic potential for AML. Methods: Mouse embryonic stem cells (mESC) were cultured and treated with Yoda-1 and GsMTx4. PIEZO1 expression in AML and healthy donors was analysed through RNAseq databases (Bloodspot, GEPIA2 and MILE study) and corroborated by ICC staining of human samples. Lastly, mononuclear cells in viability from AML or healthy donors were cultured in vitro for dose-response curves to Yoda-1 and GsMTx4 and in methylcellulose to analyse the phenotype and proliferation under those treatments. Both imaging and immunophenotyping with flow cytometry were performed in those samples. Results: When analysing the expression of PIEZO1 in AML, it was seen that Piezo1 was higher in AML compared to healthy donors, and interestingly, there was a much higher expression in AML inv(16), same chromosome as PIEZO1 is (Figure 1A). We observed that activation of Piezo1 in mESCs led to a higher expression of stemness marker Oct3/4 (Figure 1B), suggesting that it is involved in the stemness state of haematopoietic stem cells. Furthermore, we observed a dramatic effect of both Yoda-1 and GsMTx4 in leukaemia haematopoietic cells (LSCs) from AML patients grown in methylcellulose, where GsMTx4 caused an increment in the cell number and shifted the cell fate towards the erythroid lineage, while Yoda-1 decreased the number of cells and ablated the erythroid differentiation. Interestingly, such effects were barely significant in cells from healthy donors, showing a wide window for treatment (Figure 1C-D). Image:Summary/Conclusion: Our study shows that Piezo1 changes with cell differentiation and it could be a mechanism through which stem cells direct their fate. Furthermore, Piezo1 is highly expressed in AML and its blockage leads to a shift towards the erythroid differentiation while its activation blocks cell proliferation and differentiation, which such effects being much more significant in AML samples than healthy donors, suggesting a potential as therapeutic target. This work was financially supported by CRIS contra el Cancer Association (NGO) AES ISCIII (PI18/00295), ISCIII Miguel Servet (CP19/00140) and IF-Marie Sklodowska Curie Actions grant (MAtChinG – 101027864).